624407d2cf
The SFP MSA defines two option bits in byte 65 to indicate how the
Rx_LOS signal on SFP pin 8 behaves:
bit 2 - Loss of Signal implemented, signal inverted from standard
definition in SFP MSA (often called "Signal Detect").
bit 1 - Loss of Signal implemented, signal as defined in SFP MSA
(often called "Rx_LOS").
Clearly, setting both bits results in a meaningless situation: it would
mean that LOS is implemented in both the normal sense (1 = signal loss)
and inverted sense (0 = signal loss).
Unfortunately, there are modules out there which set both bits, which
will be initially interpret as "inverted" sense, and then, if the LOS
signal changes state, we will toggle between LINK_UP and WAIT_LOS
states.
Change our LOS handling to give well defined behaviour: only interpret
these bits as meaningful if exactly one is set, otherwise treat it as
if LOS is not implemented.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/E1kyYQa-0004iR-CU@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.